Search

Bacterial biofilm infection is perplexing people's life. Systemic administration of antibiotics usually causes adverse effects and bacterial resistance. How to make antibacterial agents quickly penetrate and eradicate the biofilm without adverse effects is an urgent problem. Here, polyamine-functionalized carbon quantum dots (CQDs), abbreviated as CQD600, CQD1w and CQD2.5w, are synthesized by a simple hydrothermal treatment of citric acid and branched polyethyleneimine (bPEI) with different molecular weight (MW). It is found that the antibacterial activity is promoted with high MW of bPEI, which is due to the protonated amines on the surface of the CQDs. Moreover, in terms of eradicating mature Staphylococcus aureus biofilm, CQD2.5w possesses significantly higher activity than CQD600 and CQD1w because of stronger electrostatic interactions and longer surface coronas. Additionally, the cytotoxicity test exhibits the L929 cells can keep at high survival rates even treated with 500 µg mL−1 CQDs for 3 days. In this study, the surface chemistry related to antibacterial activity and low cytotoxicity give the chance in designing and developing better CQDs for biofilm infection. [ABSTRACT FROM AUTHOR]

Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix. As a result, incorporation of AgBr/BHPVP nanocomposites did not adversely affect the flexural strength and modulus but greatly increased the Vicker's hardness of resin disks. By continuing to release Ag ions without the impact of anaerobic environment, resins containing AgBr/BHPVP nanoparticles are particularly suitable to combat anaerobic cariogenic bacteria. By reason of the combined bactericidal effect of the contact-killing cationic polymers and the releasing-killing Ag ions, AgBr/BHPVP-containing resin disks had potent bactericidal activity against S. mutans. The long-lasting antibacterial activity was also achieved through the sustained release of Ag ions due to the core-shell structure of the nanocomposites. The results of macrophage cytotoxicity showed that the cell viability of dental resins loading less than 1.0 wt% AgBr/BHPVP was close to that of neat resins. The AgBr/BHPVP-containing dental resin with dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing second caries and prolonging the longevity of resin composite restorations. Graphical Abstract: [ABSTRACT FROM AUTHOR]

In this work, a cationic polymer, N-alkylated poly (4-vinylpyridine) was applied for the surface functionalization of nanodiamond (ND). The facile route not only settled the problems of agglomeration and poor dispersion stability of ND but also rendered the nanomaterial antibacterial property. Chemical modification of the particles was confirmed by FT-IR spectroscopy and HNMR, and the cationic polymer contents were determined by TGA studies. The particle diameters and dispersity of functionalized NDs were investigated by TEM and DLS measurements. It was found that extremely tight core aggregates (100-200 nm) were broken into tiny nanoparticles (20-30 nm) through functionalization with NPVP-propyl or NPVP-hexyl, which gave stable and homogeneous functionalized ND particles in colloidal solution. The antibacterial tests against Gram-positive Staphylococcus aureus ( S. aureus) and Gram-negative Escherichia coli ( E. coli) showed that the cationic polymer-modified ND exerted certain antibacterial activity. The FE-SEM images indicated that NPVP-hexyl-ND particles were attached to the cell wall surface of E. coli, which subsequently led to the formation of nanoscale holes on cell membrane and eventually the serious destruction of cell wall. We suspected that the interaction of NPVP-hexyl-ND with bacteria may come from the electrostatic interactions, the intermolecular and surface forces between functionalized nanoparticles and cell membranes, which may damage the outer membranes of bacteria and result in cell death. [ABSTRACT FROM AUTHOR]

An antibacterial and biodegradable composite hydrogel dressing integrated with microspheres is developed for drug delivery and wound healing. The mechanism of gelation is attributed to the Schiff-base reaction between aldehyde and amino groups of oxidized alginate (OAlg) and carboxymethyl chitosan (CMCS). To enhance antibacterial and mechanical properties, tetracycline hydrochloride (TH) loaded gelatin microspheres (GMs) were fabricated by an emulsion cross-linking method, followed by integrating into the OAlg-CMCS hydrogel to produce a composite gel dressing. In vitro gelation time, swelling, degradation, compressive modulus and rheological properties of the gel dressing were investigated as the function of microsphere ratios. With increasing ratios of microspheres from 10 to 40 mg/mL, the composite dressing manifested shorter gelation time and lower swelling ratios, as well as higher mechanical strength. Comparing to other formulations, the gel dressing with 30 mg/mL microspheres showed more suitable stabilities and mechanical properties for wound healing. Also, in vitro drug release results showed that the loaded TH could be sustained release from the composite gel dressing by contrast with pure hydrogels and microspheres. Furthermore, powerful bacteria growth inhibition effects against Escherichia coli and Staphylococcus aureus suggested that the composite gel dressing, especially the one with 30 mg/mL GMs containing TH, has a promising future in treatment of bacterial infection. [ABSTRACT FROM AUTHOR]

Magnetic recyclable bactericidal nanocomposites (Fe3O4@PDMC) were well-designed and prepared by coating of Fe3O4nanoparticles with quaternarized N-halamine polymers via the free radical polymerization process. In which, 5,5-dimethylhydantoinyl-(3-ethyl-methacrylamine)propyl dimethylammonium bromide (DEMPA), a new monomeric N-halamine precursor, was used as a coating material as well as the dual-functional bactericidal agent. The developed Fe3O4@PDMC nanocomposites exhibited suitable size and super-paramagnetic responsibility. The antibacterial results showed that the Fe3O4@PDMC nanocomposites had excellent biocidal abilities againstStaphylococcus aureus(gram-positive) andEscherichia coli(gram-negative). Furthermore, the TTC (Triphenyl Tetrazolium Chloride)–dehydrogenase activity assay confirmed that the reductions of the bacteria were mainly attributed to powerful biocidal effects of the coating polymer instead of bacteria capture by the cationic surface. Interestingly, due to the magnetic responsive performance of Fe3O4, the as-prepared Fe3O4@PDMC nanocomposites can be recycled by a magnet and reused for antibacterium through the quenching/rechlorination procedure. All the results presented in this study show that the proposed Fe3O4@PDMC nanocomposites could be a competitive candidate for water purification systems and household sanitation. [ABSTRACT FROM AUTHOR]

The bactericidal magnetic nanoparticles were prepared by modifying magnetic nanoparticles (MNPs) with -halamine polymer coating and quaternary ammonium polymer coating via a two-step soap-free emulsion polymerization method. The success of the surface functionalization was confirmed by Fourier transform infrared (FT-IR), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and zeta-potential measurement. The results of antibacterial tests showed that the functional MNPs exhibited excellent antibacterial efficiency against both Gram negative bacteria E. coli and Gram positive bacteria S. aureus. Meanwhile the nanoparticles could be removed easily from water by an external magnetic field after antibacterial tests. Antibacterial nanoparticles (NPs) were prepared by modifying magnetic NPs with N-halamine/quaternary ammonium polymer coatings via soap-free emulsion polymerization and chlorination treatment process. The combination of N-halamine and quaternary ammonium greatly improved the antibacterial activity of the functionalized magnetic NPs. The as-prepared NPs with excellent antibacterial efficacy and removability were believed as potential material in water sterilization. [ABSTRACT FROM AUTHOR]

We present a simple and facile approach for preparing antibacterial magnetic nanoparticles, which were modified with quaternarizedN-halamine based cationic polymer (CPQN). The CPQN functionalized magnetic nanoparticles (MNPs-CPQN) were characterized by X-ray photoelectron spectra, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and thermogravimetric analysis. Antibacterial properties were investigated with Gram positive bacteriaS. aureusand Gram negative bacteriaE. coli. Antibacterial assessment showed that the MNPs-CPQN could eliminate nearly 100% ofS. aureusand 99.9% ofE. coli(107-8CFU/mg nanoparticles) in 5 min, while the bactericide rate of quaternizedN-halamine precursor based cationic polymer coated magnetic nanoparticles (MNPs-CPQNP) were 99.6 and 95.2%, respectively. The prepared nanoparticles exhibited a good response to an external magnetic field and had a saturation magnetization of 36.6 emu g−1. On the basis of their excellent antibacterial properties and magnetic responsiveness, the MNPs-CPQN would be a promising antibacterial material for water disinfection. [ABSTRACT FROM PUBLISHER]

ABSTRACT A viable method for coating of cellulose fiber with quaternarized N-halamine is reported in this article. The use of quaternary ammonium salt group in combination with N-halamine group can reinforce the antibacterial activity. The chemical structure of as-synthesized N-halamine precursor 4-(Bromo-acetic acid methylester)-4-ethyl-2- oxazolidinone (BEO) was characterized by 1H-NMR. The cellulose fibers were characterized by Fourier transform infrared spectra and X-ray photoelectron spectra. The spectra data confirmed that the quaternarized N-halamine-grafted cellulose fibers were successfully obtained. The antibacterial properties of functional fibers were challenged with both Gram positive and Gram negative bacteria. The antibacterial tests and showed that the as-prepared antibacterial cellulose fibers exhibited powerful and rapid bactericidal performance against both Gram negative E. coli and Gram positive S. aureus. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42702. [ABSTRACT FROM AUTHOR]

ABSTRACT Bi-functional antibacterial material was prepared by co-grafting N-halamine and quaternary ammonium salt monomers from cellulose fiber. The grafted fiber was characterized by Fourier transform infrared spectra, and X-ray photoelectron spectra. The N-halamine derived from the precursor 4-[(acryloxy)methyl]-4-ethyl-2-oxazolidinone via chlorination treatment and the oxidative chlorine (Cl+) leaching behavior were investigated. The antibacterial activities of singly (only QAs-functionalized or only Cl+-releasing) and dual (QAs-functionalized and Cl+-releasing) functional cellulose fibers were tested against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Compared to singly functionalized formulations, the bi-functional cellulose fiber exhibited excellent and rapid bactericidal performance against both E. coli and S. aureus. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40070. [ABSTRACT FROM AUTHOR]

The surface contact disinfecting technique is a newly developed method for water sterilization. In this paper, the grafted quaternary ammonium salts (QAS) antibacterial fibers were prepared and designed to apply for the surface contact disinfecting process in water treatment. The antibacterial fibers were directly prepared by grafting methacryloxylethyl benzyl dimethyl ammonium chloride (DMAE-BC) onto cellulose fiber using thiocarbonate-H2O2 redox system. All kinds of factors in the grafting reactions, such as reaction time, reaction temperature, monomer concentration, initiator concentration, which influence the percentage of grafting, were studied and optimized. The modified cellulose fibers were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope(SEM). The effects of the percentage of grafting of the grafted cellulose fibers on bactericidal activity were also studied. The spread plate method was used to characterize the bactericidal activity. The disinfection process was further investigated by directly observing the morphology of the bacterial cells adsorbed on the antibacterial fibers with SEM and measuring extracelluar total protein concentration in suspension. The poly(DMAE-BC)-grafted cellulose ?ber was found to exhibit particularly high activity against E.coli. [ABSTRACT FROM AUTHOR]

For cartilage tissue repairing, it remains a key challenge to design implant materials with antibacterial activity, proper degradation rate and mechanical property. In this research, antibacterial nanodiamonds (QND, QND-Ag) modified acrylate-terminated polyurethanes (APU) were prepared. By the addition of nanocomposites, the crystallinity of modified APU obviously increased, which indicates a strong interaction between NDs and APU. Tensile and compression tests were carried out to evaluate the improved mechanical properties. Compared with APU, APU(10%PEG)/QND-Ag possessed the increased modulus and strength, a nevertheless slight decrease in elongation at break. Due to the dual actions of contact-killing of cationic polymers and release-killing of the Ag NPs, QND-Ag-containing polyurethane showed excellent antibacterial activity against Staphylococcus aureus. Moreover, APU containing polyethylene glycol showed a significant increase in degradability rates. Consequently, owing to the dual effect of crystallinity and hydrophilicity, our modified APU exhibited the proper degradation rate adaptable to the healing rate of cartilage tissue. Furthermore, the CCK-8 results demonstrated that synthesized samples were low toxic. Therefore, APU(10%PEG)/QND-Ag holds great promise for the application of cartilage tissue repairing. [ABSTRACT FROM AUTHOR]

Research on the cutting-edge nano-fillers for designing dental restorative materials with excellent mechanical property and antibacterial performance is demanding and provoking work. In this study, we fabricated silver-loaded polycation functionalized nanodiamonds (Ag/QNDs) that harbored dual biocidal modes for use as reinforced filler in dental resin. As a result, by reason of homogeneous dispersion and strong bonding with resin matrix, Ag/QNDs-reinforced resin exhibited great improvement of Vickers hardness, flexural strength and modulus as compared with pure resins. Due to the combined bactericidal effect of Ag + and cationic polymers, Ag/QNDs-containing composites had an excellent antibacterial activity even at a concentration of 1.0 wt% but without significant cytotoxicity. Therefore, development of the Ag/QNDs hybrid is expected to aid in significant improvement of lifetime and quality of dental restorative resin. [ABSTRACT FROM AUTHOR]

A facile, economical and green synthetic route was developed to fabricate magnetic nanocomposite arming with silver nanoparticles (AgNPs) for antibacterial application. In this synthesis, two natural compounds, positively charged lysozyme (Lys) and negatively charged tannic acid (TA), were alternately deposited on Fe 3 O 4 nanoparticles (IONPs) surface by layer-by-layer (LbL) self-assembly technique. And then AgNPs were embedded by an in situ reduction of Ag + so as to achieve complementary antibacterial functions to act against Gram-positive and Gram-negative bacteria. In which, the deposition of AgNPs can be facilely achieved without any external reducing agent. The systematic antibacterial assays showed that synthesized nanocomposites had high antibacterial efficiency against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus . Investigation of antimicrobial mechanism suggested that these nanocomposites could lead to the disorganization of bacterial cytomembrane and leakage of cytoplasmic contents. Moreover, the permeable alteration of cytoplasmic membrane may facilitate the Ag + released from nanocomposite entering into cells, and further cause the bacterial death. Due to the excellent magnetic responsive performance of IONPs, the nanocomposites can be easy recovery by external magnetic field from application environment after disinfection. By taking advantages of such properties, the developed nanocomposite could be an ideal candidate with promising antibacterial applications. [ABSTRACT FROM AUTHOR]